package Example10;

import java.sql.*;
import java.util.Scanner;

public class Login {
    public static void main(String[] args)  throws SQLException {
        Statement stmt = null;
        ResultSet re = null;
        Connection conn = null;
        try {
            //1. 注册数据库驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2. 通过DriverManager获取数据库连接
            String url =
                    "jdbc:mysql://localhost:3306/jdbc?serverTimezone=GMT%2B8&useSSL=false";
            String username = "root";//数据库账户
            String password = "123456";
            conn = DriverManager.getConnection(url, username, password);
            /**
             * 终端用户登录
             *
             */
            Scanner sc = new Scanner(System.in);
            System.out.println("用户登录");
            System.out.println("请输入你的姓名");
            String userName = sc.next();
            System.out.println("请输入你的密码");
            String userPwd = sc.next();
            String loginSql = "select * from users where name = ? and password = ?";
            PreparedStatement pm = conn.prepareStatement(loginSql);
            pm.setString(1, userName);
            pm.setString(2, userPwd);
            re = pm.executeQuery();//executeQuery返回多行数据 executeUpdate()返回一个int
            //3. 通过Connnection对象获取Statement对象
            stmt = conn.createStatement();
            // 4.使用Statement执行SQL语句
            String sql = "select * from users";
            re = stmt.executeQuery(sql);
            while (re.next()) {
                int id = re.getInt("id");
                String name = re.getString("name");
                if(id>0){
                    System.out.println(name+"登录成功");
                    //如果数据库中有两个同名同密码的人 直接结束循环 只提示第一人
                    break;
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }finally {
            if ( re  !=null){
                try {
                    re.close();
                }catch (SQLException e){
                    e.printStackTrace();
                }
                re = null;
            }
            if (stmt!=null){
                try {
                    stmt.close();
                }catch (SQLException e){
                    e.printStackTrace();
                }
                stmt = null;
            }
            if (conn!=null){
                try {
                    conn.close();
                }catch (SQLException e){
                    e.printStackTrace();
                }
                conn = null;
            }
        }
    }
}
